I am getting inconsistent compatibility with PAL GCN games launched through the Disc Channel on a NTSC-U Wii modded with a Wiikey.

Some PAL games, like Doshin the Giant, work fine. Others, like DBZ Budokai 2 boot with a black & white jumping screen. I tried this game both in a multigame ISO and burned on a mini DVDR. It works fine when launched from a GameCube Backup Launcher. I also tried it on my modchipped GameCube, and it also gives me a b&w jumping screen.